1. Field of the Invention
The present invention relates to a phthalocyanine compound having high durability and useful as a functional dye.
2. Description of the Related Art
Phthalocyanine compounds are widely used not only as dyes or pigments having high durability, but also as functional dyes. In particular, Japanese Patent Application Laid-Open (JP-A) No. 2003-94828 and the like disclose the use of a phthalocyanine compound, which is substituted by an alkyl group, an aryl group, or a heterocyclic sulfonyl group at α position, as a dye in a recording layer of an optical information recording material such as a CD-R or the like. All of the patents, patent publications, and non-patent literature cited in the specification are expressly incorporated by reference herein. Phthalocyanine compounds having a sulfonyl group as a substituent at α position have preferable absorption characteristics; however all of the well-known compounds are oil-soluble, and the use and using methods thereof are limited. In addition, a water-soluble phthalocyanine compound having a sulfonyl group as a substituent at β position is disclosed in JP-A No. 2004-323511, but an aqueous solution thereof shows only a broad spectral light absorption spectrum derived from its aggregates.